3D printerers Wiki
''Welcome to the Wiki Hi everyone, welcome to our wikiblog about 3D printing. We will be updating this page with information about 3D printing and looking into different types of 3D printing available. Kavita - Material Jetting Zakii - Powder Bed Fusion (metals) Mathieu - powder bed fusion (polymers) Yicai - Photopolymerisation Jiali - Binder jetting Rebecca - Overview of 3D printing Ozair - Fused Deposition Modelling (FDM) 'Introduction to 3D Printing' 3D printing is the process by which a physical object is made from a three-dimensional digital model; this typically involves the addition of many thin layers of a material in succession. 3D printing is quick, cost-effective and allows complex ideas to be simplified through physical models. For these reasons, 3D printers have a wide variety of applications such as for product development, architecture and within the medical sector. The additive manufacturing (3D printing) process usually consists of 5 steps: 1. '''Modelling' – A digital model is produced, most commonly by computer-aided design (CAD). 2. STL conversion & file manipulation – CAD model converted to an STL file. The file is then imported into a slicer program allowing customisation of build parameters such as support, layer height and orientation of parts. Now, the model is ready to be printed. 3. Printing – The print material is loaded into the printer and the additive manufacturing machine follows an automated process to produce the object. 4. Removal of prints – The complexity of this step depends on the printing method used, ranging from simple separation to precise extraction from build plate. 5. Post processing – This step also varies depending on method used. However, some general techniques include tumbling, high-pressure air cleaning, polishing and colouring. There are 6 main types of 3D printing: Material Extrusion, Vat Polymerisation, Powder Bed Fusion(metal), Material Jetting, Binder Jetting and Powder Bed Fusion(polymers). ''Types of 3D printing 1. '''Fused Deposition Modelling (FDM)' Fused Deposition Modelling (FDM) is the process by which material is added to an object through the selective deposition of melted material. Such materials include thermoplastic polymers in their filament form. The material is drawn through the nozzle at a steady pressure and is heated as it does so; this ensures that it is in its semi-liquid state and therefore ready to be deposited on the previous layer. The process is repeated several times and subsequent layers are fused with previous layers while in their melted state. Solidification of these layers can commence shortly after at room temperature. FDM is the most commonly used process in 3D printing. Advantages include low cost and high accessibility. This is because ABS plastic, a common thermoplastic polymer, can be utilised during the deposition process. Drawbacks include low accuracy, poor surface quality and only a limited number of suitable thermoplastic polymers. The quality of the final product is dependent on the constant pressure applied during deposition, something that requires great accuracy throughout. 2. Binder Jetting'Alkaios Bournias Varotsis, 3D Hubs. 12 December 2017. Introduction to Binder Jetting 3D printing. Internet. Available from: https://www.3dhubs.com/knowledge-base/introduction-binder-jetting-3d-printing 16 October 2018. In ''binder jetting, a binder is selectively deposited to the powder bed to form a solid part one layer at a time. For doing this, firstly we need to build up a powder foundation. Secondly, a binding agent such as a glue mixing with inkjet nozzles are carried and passed over the foundation powder layer. A few droplets of them are then deposited selectively onto the powder for bonding according to the final solid shape that we want. Thirdly, when one layer has been formed, the build platform moves downwards and is again covered by a thin layer of powder for formation of the solid part in next layer. Finally, after printing enough layers, the entire substance is fully covered by powder and left to cure and gain strength. The powder at the surface is then removed by pressurised air. We can then take out the solid product easily. REFERENCE: Alkaios Bournias Varotsis, 3D Hubs. 12 December 2017. Introduction to Binder Jetting 3D printing. Internet. Available from: https://www.3dhubs.com/knowledge-base/introduction-binder-jetting-3d-printing 16 October 2018. 3. 'Material Jetting'1. https://www.3dhubs.com/knowledge-base/introduction-material-jetting-3d-printing 2. http://www.lboro.ac.uk/research/amrg/about/the7categoriesofadditivemanufacturing/materialjetting/ Reference for Material Jetting.jpg: https://goo.gl/images/DAHicq Material jetting works similarly to a 2D printer. Droplets of the chosen photosensitive material are released (jetted) from a print head, either in a continuous fashion or from using the Drop On Demand (DOD) method 1. The droplets are hardened by UV light in order to form the layers needed to build the product. Multiple materials and colours can be used during the process. For continuous material jetting, the droplets are charged when released from the print head and are positioned with great accuracy using deflection plates 2. There can be multiple print heads attached which allows the whole layer to be printed in one pass 1. The use of multiple print heads allows multiple materials or multiple colours to be used at once, as well as the ability to add supports, which can be dissolved later, to the structure. Not only can products be made from multi-materials or multicolours, these properties can be achieved by building different parts in different materials/colours or by mixing materials together before starting printing. '''Supports are always required when using this technique to print objects. They are generally printed in a soluble material which can be removed post production by a high pressured water jet, sodium hydroxide or an ultrasonic bath. One has the option of printing with either a matt or glossy finish. For the matt finish, a thin layer of support material is added to all surfaces, while for glossy, only surfaces in contact with the support structure will be matt. A matt finish should be used for when a uniform finish and accuracy is required on the product, while glossy is used for when a smooth shiny surface is required. The materials that are able to be used in this process are flexible and resistant to high temperatures, however, they are brittle. Benefits of this process are that there is little waste as excess droplets are recycled 2; objects with multiple materials and colours can be made from just one process; the products produced can have smooth surfaces that are comparable to those formed in injection moulding and have a high dimensional accuracy 1. However, the products produced have poor mechanical properties and so are generally suited to prototypes only; the materials are photosensitive and so may degrade overtime; support is often required too; the cost of material jetting is high and there is a limited number of materials that can be used. Reference: 1. https://www.3dhubs.com/knowledge-base/introduction-material-jetting-3d-printing 2. http://www.lboro.ac.uk/research/amrg/about/the7categoriesofadditivemanufacturing/materialjetting/ 3. https://goo.gl/images/DAHicq 4. Photopolymresisation 3D Printers 27/10/2018 Photopolymerisation 3D printers use liquid photopolymer resins to construct the model layer by layer. Resins in the liquid state are solidified using UV light which cures the resin, making it hard. Prototypes are manufactured layer by layer and the result of vat photopolymerisation 3D printers can offer the highest resolutions of all types of 3D printers. There are 2 types of of Vat Photopolymerisation printers: SLA Stereo lithography (SLA), is the World's first 3D printing technology, invented in the 1980s. Models, prototypes and patterns are created by selectively curing a polymer, a liquid resin, layer by layer using ultraviolet (UV) laser beam. This beam causes chains of molecules, to link and form polymers, making up the body of the 3D solid. The materials used come in a liquid form and are photosensitive thermostat polymers. Different types of resin formulations with different mechanical, optical and thermal properties can be used to match different needs. This type of 3D printing is the one which gives the highest resolution and accuracy and the smoothest surface finish of all plastic 3D printing technologies existing today. It also provides the best versatility and the clearest details. Two galvanometers, one on the X axis and one on the Y axis are used to move the laser beam across the print area to solidify the liquid resin. This breaks down the design into a series of points and lines given to the galvanometers as a set of coordinates. SLA is a great option for highly detailed prototypes requiring tight tolerances and smooth surfaces however this technology makes brittle parts, generally not suitable for functional prototypes, and their mechanical properties and visual appearance will degrade overtime if they are exposed to sunlight. Also, post-processing is usually needed to remove support structures required to make the prototype. SLA is best suited to make visual prototypes of a wide range of sizes. DLP Digital Light Processing is another type of 3D printing based on photopolymerisation. DLP follows similar principles as SLA printing but in this case, a digital projector screen is used to flash a single image of each layer to solidify the resin. The image of each layer is composed of square pixels, resulting in a layer formed from voxels, small rectangular bricks. The resolution depends on how many voxels are available, which depends on the projector used. One of the limitations of DLP is the size-resolution of the prototypes produced. The use of small voxels for a higher resolution constrains the size of the overall build area by shrinking the entire image. Bigger prototypes will use bigger voxels, decreasing the resolution of the product. DLP printers are a better choice than SLA printers when large parts with lower resolution are required as this technology will produce the prototype in a lower time. Reference: 27/10/2018 5. SLS'''https://www.3dhubs.com/knowledge-base/introduction-sls-3d-printing SLS is a 3D printing procedure that is used for prototyping functional polymer components and for small production runs of items as it has very high design freedom and high accuracy. A component is formed by the following additive process: # Firstly the powder heated to just under its melting point and then it is spread very thinly onto the build area. # Next a CO2 laser scans the contour of the next layer, splintering together the polymer powder particles. This is done for the entire cross section of that layer of the component being built. # When this layer has been completed the process is repeated many many times until the component has been built. The components are fully encapsulated within the polymer powder and requiring you to extract the components via compressed air or another blasting media. This stage, however, can only be completed once the material powder bin has cooled down which can take upwards of '''12 hours. Once cleaned out the left over powder can be mixed in with fresh polymer powder and re-used in later projects. Manufacture of many components can be done at once within the powder as it acts as a supporting material keeping everything in place whilst the components are made and cool into position. https://www.3dhubs.com/knowledge-base/introduction-sls-3d-printing ''Pros and cons '''Fused Deposition Modelling (FDM)' Pros: • Low cost • High accessibility Cons: • Low accuracy • Poor surface quality • Limitied number of suitable thermoplastic polymers Photopolymerisation Pros: • Very high resolution • Can make a wide range of sizes Cons: • Makes brittle parts • Visual appearance will degrade over time if exposed to sunlight • Post processing needed to remove support structures Powder bed fussion Pros: • Low cost • Wide material choice • Powder recycling Cons: • slow and long print time • Low quality surface finish • Post processing needed to remove support structures • High power usage (uses a lot of energy to create parts Binder jetting Pros: • Low cost • Not limited by any thermal effect • Batch production Cons: • Lower mechanical properties • Rough details printed •Limited material selection Material jetting Pros: • Smooth parts printed • High dimensional accuracy Cons: • Material properties degrade over time Ethics 1. Low level of entry. '''3D printers are readily available with many open source designs available on the internet. 2. '''3D printing can make dangerous objects such as guns currently. In the future other dangerous objects could be designed and as the technology gets better they could be made in metal which is more harmful with a larger extend of danger. 3. Barriers of entry may not be strict enough for more technical and sensitive areas of 3D printing, such as for drug design. Don't want anyone just to be able to print their own drugs or for someone within companies to take advantage of the drug printing machines for personal gain. Regulation and rules within businesses is required to control this. 4. There may be unknown consequences from 3D printing: chemicals used or the products of the reaction may be harmful to the environment or carcinogenic. These effects may not be discovered for a while as they may have a long term effect. 5. Also 3D printers use a lot of energy which is damaging to the environment if not from renewable sources. Discussion On The Future of 3D Printing On medical area: 3D printing of prosthetic limbs; Very expensive at the moment but should it be paid for on the NHS? Is it very accurate to create a precise fit of the joint? How quickly can the joints be scanned and how quickly can the limbs be made? If someone has a 3D printed prosthetic limb in sport does that give them an advantage to the rest of the field (as it may be lighter, stronger, better made and more precise in its dimensions) ? Should the NHS commit a lot of investment in science so that future costs will reduce majorly and phase out current methods of prosthetic limb manufacturing? Trip to National Physical Laboratory On 13th of February, we went to National Physical Laboratory (NPL) ''for visiting. 1.Mainly looked at the 3D printing lab: * Vat polymerisation printers (printing and curing the obejcts) * Fused Filament printers: Printing of the spinal vertebrate * Discussion on the 3D printing process – use of CURA, setting up the printer and running a print. 2.General visit at the NPL: * Talk for introduction of NPL: - Metrology Laboratory in Teddington - Accurately define seven SI units; kilogram, metre, second, kelvin, candela, ampere and mole. - The key areas of research: 1) Advanced manufacture; 2) Medical; 3) Digital; 4) Environmental. * Lab tour SPECT laboratory, Airborne nanoparticles and thermal imager research (diabetes (feet), radioactive containers, finger prints) ''Video Storyboard as preparation ''Latest activity'' Photos and videos are a great way to add visuals to your wiki. Add one below! Category:Browse